1) Field of the Invention
The present invention relates generally to folding agricultural implements and, more specifically, to a folding cylinder structure for implements such as sprayers having large folding sections which are sequentially folded between storage and transport positions.
2) Related Art
Implements such as agricultural sprayers include large folding booms which are built in sections to fold for transport and unfold for application of chemicals. The unfolded boom can be as long as 90 feet or more, and the folding and unfolding sequences must be carefully controlled to avoid excessive stresses on the boom and folding cylinders. To achieve proper sequencing, manufacturers have typically resorted to an array of position-responsive switches strategically placed near the bottom of boom joints. These switches are connected to electrohydraulic valves and to operator control switches in the sprayer cab. The switches on the boom are exposed to harsh environmental conditions which adversely affect switch operation and often result in boom fold malfunction. Troubleshooting and repairing a faulty fold system often is difficult and time consuming. In addition, the operator control switches in most sprayer cabs are located remote from other controls such as the hydro controller on hydraulically driven sprayers so the operator has to turn from the normal operating position to activate the fold sequence.
Therefore, it is an object of the present invention to provide an improved foldable boom arrangement. It is another object to provide such a structure which overcomes most or all of the aforementioned problems. It is yet another object to provide such an arrangement which is more durable, requires less maintenance and has reduced component and manufacturing costs compared to at least most previously available boom folding arrangements.
It is a further object to provide an improved foldable boom arrangement which obviates externally mounted switches on the boom. It is another object to provide such an arrangement which is more reliable and more convenient to operate than at least most previously available foldable boom arrangements. It is another object to provide such an arrangement which simplifies troubleshooting and repair.
It is still another object of the present invention to provide an improved foldable boom arrangement, particularly useful with very large folding boom implements including sprayers with working widths in excess of 90 feet, which reliably establishes proper folding sequence to reduce forces on the boom sections and folding cylinders. It is a further object to provide such an arrangement having an improved sequencing circuitry.
It is yet a further object of the invention to provide an improved cylinder and cylinder extension sensor for a foldable boom arrangement. It is another object to provide such a cylinder and sensor wherein switching elements are better protected from the harsh environment of a sprayer. It is another object to provide a compact control circuit for such a sensor supported primarily by the cylinder for ease of assembly, troubleshooting and repair.
A foldable boom arrangement or the like constructed in accordance with the teachings of the present invention includes a large boom having an inner section pivotally supported from a frame for movement between an outwardly extended working position and a folded transport position by an inner fold cylinder located at a first hinge point. The boom includes an outer section pivotally connected to the outward end of the inner boom at a second hinge point and movable relative to the inner section between folded and unfolded positions by an outer fold cylinder. Each of the cylinders includes an internally mounted cylinder position sensor which preferably is a proximity switch threaded into the cylinder and sensing the presence or absence of a magnet mounted for movement with the cylinder piston. When the cylinder rod is at the end of its stroke, the magnet projects into the sensor zone to establish a position signal. The internally mounted switch is protected from the harsh environment encountered by a sprayer, and wiring is simplified. The magnet also attracts harmful metallic contaminants in the hydraulic fluid to eliminate a source of hydraulic system wear.
The switches are connected to a fold sequence circuit which includes operator switches located adjacent the main sprayer controller switches in the sprayer cab so the operator does not have to turn away from his normal operating position to activate the folding or unfolding cycle. The inner fold cylinder proximity switch controls the extension or unfold sequence while the outer fold cylinder proximity switch controls the fold sequence. The control circuit including proximity switches and operator switches is relatively simple, inexpensive and easy to attach and operate. A substantial portion of the circuit is housed integrally with the proximity switches to greatly simplify assembly, troubleshooting and repair.
Various boom operating positions can be quickly and easily established by the operator, including fully unfolded wide field operation, and inner section unfolding only on one or both sides for narrower operation. To change from narrow operation to wider operation, the operator switch for each side is simply pressed and held until the proximity switch provides the signal that indicates the unfolded position has been achieved and hydraulic flow to the cylinders is deactivated. The larger inner boom section cannot be folded until the outer boom section is first folded against the inner boom section so that stresses on the boom and boom cylinders are minimized.
These and other objects, features and advantages of the present invention will become apparent to one skilled in the art upon reading the following detailed description in view of the drawings.